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Frequently asked about the Mass Percent
What does the Mass Percent do?
The Mass Percent solves the common stoichiometry, gas laws and solution chemistry question: % w/w. Enter your numbers on the left, the answer updates instantly on the right — no submit button, no signup.
Is the Mass Percent free to use?
Yes. Every calculator on CalcMaster is free, has no usage caps, requires no signup, and shows no ads. The site is open-source-friendly and supported entirely by the author.
Does the Mass Percent work on mobile?
Yes. CalcMaster is fully responsive and installable as a PWA — on Android tap the browser menu → "Add to Home Screen"; on iOS Safari → Share → "Add to Home Screen". After installing, the Mass Percent works offline.
Where is my input stored?
Nowhere by default. Your inputs live in your browser's memory while you're on the page; a copy of your recent calculations is saved to localStorage on your device so the History page works. Nothing is sent to a server unless you explicitly enable cloud sync.
Can I trust the formula in the Mass Percent?
The math is sourced from peer-reviewed and standard public formulas; you can read the formula in the result card. For decisions involving real money or health, always cross-verify with a qualified professional — calculators are educational, not advice.